What is the best Value Card for me?

My question is basically in the title, but to elaborate more on what I am looking for I will give you guys a list of games I want to be playing at what settings.

Game: League of LegendsRes: 1080pfps Goal: constant 300+

Thats about it...lol. Oh, and I'd like to hook up 3 monitors to 1 video card. Thats about all my computing needs right there.

I am willing to spend anywhere up to $450. I've been looking at some GTX 680's lately but I don't know if thats overkill for what I actually need. I am trying to get the most out of my money for what I actually need this time instead of trying to get something "future proof".